7.已知定点A(-2,0),B(3,0),动点M(x,y)满足向量MA*向量MB=x*2,则点M的轨迹方程是—
7.已知定点A(-2,0),B(3,0),动点M(x,y)满足向量MA*向量MB=x*2,则点M的轨迹方程是——————